Coil-winding machine



Sept. 6, 1949. H. v. KNAUF, JR 2,481,314

COIL WINDING MACHINE Original Filed July 31, 1946 4 Sheets-Sheet l min" INVENTOR BY Hart}; \[Knauf Jr.

w ILWLV ATTORNEY Sept. 6, 1949. H. v. KNAUF, JR 2,481,314

COIL WINDING MACHINE Original Filed July 31, 1946 4 Sheets--Sheet 2 INVENTOR Hdrrg V. Knauf Jr.

ATTORNEY Sept, 6, 1949. H. v. KNAUF, JR 2,481,314

COIL WINDING MACHINE 4 Sheets-Sheet 3 Original Filed July 31, 1946 i iif fgj T Harv v 1%? Jr. 65%

ATTORNEY 6, 1949. H. v. KNAUF, JR 2,481,314

COIL WINDING MACHINE Original Filed July 51, 1946 4 Sheets-Sheet 4 m w M N unglllllw BY m \mmuf Jr. $1

ATTORNEY w A INVENTOR Patented Sept. 6, 1949 COIL-WINDING MACHINE Harry V. Knauf, Jr., Oakiyn,

Radio Corporation of America,

oi. Delaware Original application 687,447. Divided an This case is a division of copending application Serial No. 687,447 filed July 31, 1946.

This invention relates to the art of winding coils, particularly to improvements in machines for making form-mounted inductance coils and, while not limited thereto, will be described as applied to the manufacture of voice coils for loudspeakers.

Loudspeaker voice coils usually comprise either a single or plural layer helix wound upon a cylindrical impregnated-paper form which is no thicker than, say, 0.005 of an inch. When made by mass production methods such coils have heretofore been wet-wound, i. e. the adhesive impregnant which binds the wire and the coil form into a unitary structure fluid state during the Winding operation'and is subsequently evaporated, as in a drying oven. Wet-winding is an untidy procedure and is an expensive one as well. Furthermore, wet-winding results in an unusually high percentage of rejects. Why this is so will be apparent when it is appreciated that since the bonding agent must be applied in an extremely fluid condition it can contain only a small percentage of solid adhesive material, hence the strength of the bond between the parts is relatively poor even in those units N. J., assignor to a corporation July 31, 1946, Serial No.

11 this application September 2'1, 1946, Serial No. 699,617

3 Claims. (Cl. 242-43) is applied in a highly which are thoroughly dry and otherwise perfect.

Thorough drying is not always achieved in practice because a wet-wound coil immediately acquires a surface skin which traps the liquid solvent and renders its escape difficult even under accelerated drying conditions. Incompletely dried coils may retain the trapped solvent for many months and when such a coil is subject to normal vibrational stresses (i. e., in the audio frequency range of from, say, to say, 10,000 cycles per second) its turns may creep and ruin the performance of the loudspeaker. Prolonged drying, on the other hand, may cause the coil form to shrink and the coil to warp, making it necessary to expand the form in an effort to restore the assembly to its original shape and dimensions.

Accordingly, the principal object of the present invention is to obviate the foregoing and other less apparent objections to present day wetwound coils and to provide an improved apparatus for winding voice coils and analogous (formmounted) inductors.

Another and related object of the invention is to provide an improved apparatus for the drywinding and embedment of coils and one which, in its use, dispenses with all auxiliar moulding and other shaping mechanisms. (Cf. the 1924 British Patent No. 250,282 to Rickets et a1.)

The foregoing objects are achieved in accordance with the method of the parent invention, first by making, on a mandrel or arbor, a coilform having a dry coating of a synthetic resinous thermosetting adhesive material in an intermediate stage of iusibility on its outer surface, then heating the coating material (as by heatin the arbor) to render said coating tacky, then winding wire having a similar (dry) adhesive coating on the said form whereby the coating on the wire is rendered tacky by contact with the heated surface of the coil-form, and then heat-setting both coatings to the infusible stage.

Certain preferred details of procedure and construction, together with other objects and advantages of the invention will be described in connection with the accompanying drawings where- Fig. 1 is a view in perspective of a multiple coil winding machine constructed in accordance with the principle of the invention and including a detached cylindrical split-sleeve for making a coil form and a tool for removing said sleeve from the heated mandrel of the machine.

Figs. 2, 3 and 4 are end views of the split sleeve of Fig. 1 showing the manner in which the sheet material, -of which the coil form is made, is wrapped.

Fig. 5 is a fragmentary view in perspective of the machine of Fig. 1 showing the sleeve of Figs. 1 to 4 on the heated mandrel and undergoing a rolling operation for bonding the layers of sheet material together.

Fig. 6 is a longitudinal sectional view revealing the construction of the heated mandrel of the machine.

Fig. '1 is an enlarged view in perspective of one of the wire-guiding and holding means of the machine.

Fig. 8 is a view in perspective showing the winding machine in operation and including the reeling system from which the wires are fed to the coil form.

Fig. 9 is an enlarged side elevational view partly in section of one of the supply reels of Fig. 8, and

Fig. 10 is an enlarged fragmentary view in perspective of the machine upon the completion of the winding movement, with the wires broken off and held in a position to permit the removal of the coil form from the mandrel.

In applying the invention to the manufacture of voice coils, it is preferable to start with a high grade kraft paper, say, 0.006 to 0.0015 of an inch thick, and with enamel covered copper wire, of the desired gauge, and coat the paper and the wire, separately, with the thermosetting adhesive material which is allowed to dry at room temperatures to a point where all of its volatile constituents have evaporated. Any of numerous resinous adhesives having the property of becomin tacky at an elevated temperature which is lower than is required to set, or render it infusible, may be employed as the coating material. In general, all "A-stage condensation type thermosetting resins possess this desired characteristic. The adhesive properties of the coating material may be en hanced by the addition of a thermoplastic adhesive such, for example, as a vinyl resin. One satisfactory coating material formula is:

Part A Grams Gelva No. 60 (vinyl acetate resin) 200 One step phenolic resin 200' Acetone (solvent) 1000 Part B Grams Vlnylite XYSG (vinyl acetal resin) 150 One step phenolic resin 150 Ethyl alcohol (solvent) 1200 By one step phenolic resin is meant a phenolic resin in that incomplete stage of condensation (commonly known as the A stage) wherein the resin is still fusible and completely soluble. (When parts A and B of this formula are mixed there is a tendency to separate, thus the material should be agitated during the coating process.) Other, ready-mixed, thermosetting adhesives are available under various grade marks.

The dry adhesive-coated paper I from which the coil forms are made tends, usually, to curl up on its coated side la. Since the adhesive must be on the outside of the finished form it is necessary or expedient to counteract this tendency, either by tension (e. g. by running it over a smooth, warm surface and then wrapping it on a cylindrical form) or by curling the sheet in the reverse direction, as by inserting it in the slot 2a of a split metal sleeve 2 and then withdrawing it and wrapping it on the outside of the sleeve, in the manner indicated by the curved arrows in Figs. 2, 3 and 4. With the paper thus wound on the metal sleeve 2 its turns may be prevented from unwinding before the sleeve is placed on the coil winding machine by heating the coated surface at spaced points along its edge. This spot tacking operation can be done simply by touching the wrapped paper to the electrically heated mandrel or arbor 3 of the winding machine.

The machine shown in the drawings is espe-- cially constructed for the commercial practice of the invention and is provided with a rubber or similar roller 4 which is mounted on a pivoted bracket or frame 5 parallel to the arbor 3 so that the roller may be brought into contact with the rolled paper when the sleeve 2 upon which the paper I is wrapped is mounted on the electrically heated rotating arbor 3. The heat transferred through the sleeve 2 to the paper from the electrical heater element 6 (see Fig. 6) is just sulficient to soften the adhesive coating on the paper. Thus, when the handle 50: on the bracket 5 is pulled down (as shown in Fig. 5), the roller 4 is brought into contact with the paper and applies a rolling force which bonds the tacky layers of the paper together into a smooth, composite cylindrical structure. When the rolling operation is completed the roller 4 is thrown back and the tacky paper is ready to receive the wire or wires.

Any number of coils within the limits of the length of the winding arbor 3 may be wound simultaneously. As shown in Fig. 8 the machine is set up to wind nine coils. Here the nine supply spools SIS3 are supported in equally spaced relation on a triangular frame I above and to the rear of the arbor 3 and the individual wires Wl-W9 are led down around fixed rollers RI- R9 and thence forward and upward over grooved guide members Ml-M9 on a rod 8 which is mounted for axial movement, parallel to the axis of the arbor 3, under the control of a hand lever 8a which can be moved to the left and to the right on a pivot lip on the base of the machine. In setting up the wires WlW9, prior to the winding operation, the free end of each wire is held upright each by a spring clip 9 (see Fig. 7) on the outer face of the alternate (odd-numbered) of ten pairs of wire guiding fingers Fl to F20 which are mounted beneath the arbor 3 on a movable support comprising a rod I 0 which is secured at its opposite ends to the arms of a U-shape bracket or frame II. This frame H is carried on pivots llp at the base of the U and is provided with a hand lever Ila. As shown in Fig. 9 the axle of each supply spool SI etc. is provided'with a clutch l2 to facilitate replacement of the spool and with a friction brake l3 for maintaining tension on the wire throughout the winding operation.

After the coil form has been rolled and the roller 4 moved out of the way, each wire is removed from its clip 9 and placed on the tacky surface of the coil form slightly to the left of the odd-number finger, to provide an extra length of wire which when removed from the coil form comprises an attaching lead for the coil. As soon as the wires are brought into contact with the heated surface of the coil form they are held fast by the tacky adhesive thereon. The operator then raises the handle Ila of the pivoted bracket or lever means II and thus brings the wire guiding fingers FIF20 on the rod llJ adjacent to, but not touching, the rotatable heated arbor 3 upon which the sleeve 2 for coil form I is mounted. The fingers Fl etc. are maintained in the raised position, shown in Fig. 8, by means of a counter-weight l4 carried on an arm l4a (see Fig. 5) on the rear of the pivoted bracket H, and an over-center spring l5 (see Fig. 8) which is secured at one end to the rod l0 and, at its other end, to the base l6 of the machine. The lever 8a is then moved to the right. This shifts the axially movable rod 8 upon which the grooved wire guides Ml etc. are secured, to the left, and brings the said guides into the starting position.

When all wire ends have been removed from the clips 3 and applied to the coil form I, and the lever lla has been raised, the arbor 3 is rotated through as many revolutions as required to form a coil of the desired number of turns. As shown in Fig. 1 the power required to rotate the arbor 3, and to operate its conventional revolution counter I! may be applied either by means of a hand-wheel l8 or by a belt iii. In the latter case the belt may be driven by an electric motor not shown) under control of a foot actuated switch (not shown).

The limits of the length of the individual coils Cl, C2, etc. are determined by the spacing of the paired fingers FIF2, F2F3, etc. As previously set forth, the rod 8 upon which the grooved wire guides Ml etc. are mounted can be moved axially with respect to the fingers Fl etc. and the arbor 3 under the control of the lever or arm 8a. Hence, when winding a voice coil or similar plural layer structure, it is merely necessary to move the pivoted arm Be on its pivot 810 to the left at the time the wire comprising the lower layer reaches the side of the even-number fingers (F2, F4, etc.) in order to start the second or reverse-wound layer. This movement of the arm Ba to the left moves the rod 8, which carries the grooved wire-guides MI etc., to the right. Obviously, the spacing of the turns comprising either layer may be regulated, if desired, by changing the rate of movement of the lever Be as by means of a cam (not shown). In this latter event it is preferable to mount the rod 8 somewhat closer to the arbor than is shown in the drawings.

In Fig. 8, the rod 8 has reached the limit of its movement in the return (left) direction. That is to say, the wires WI-W2 etc. have reached their starting point adjacent to the faces of the odd-numbered fingers Fl, F3, etc., and the winding operation has been completed. While the bar II) is still in its raised position the operator pulls each wire over the end of the adjacent (oddnumbered) finger Fl, F3, etc., and, by so doing. places it under the spring clip 9 on the said finger, and then severs all of the wires, simultaneously, simply by pulling down the handle Ila of the pivoted supporting frame II against the biasin force of the counterweight I4 and off-center sping I5 (Fig. 8). In pulling down the handle Ila the operator may hold the handwheel I8 (Fig. 1) against rotation. This however, is not always necessary since the several turns of the coils, provide a snubbing action which is usually suilicient to prevent the arbor 3 from turning when the handle Ila is pulled down. As shown in Fig. 10, the arc of movement of the rod III upon which the guide fingers Fl, etc. are mounted is such that, when the U-shape frame II is pulled down, the free-end of the wires WI, W2, etc. are held in a readily accessible upright position and the coil ends of the wires are conveniently tacked to the adhesive on the coil form I by the force applied to the wires during the severing operation.

In order to remove the sleeve 2 upon which the coil form I is mounted from the arbor 3 it is first necessary to release the bearing 20 at the outer end of the arbor. This is done by turning two thumbscrews 2I and 22. The upper scew 2I releases the shaft 23 upon which the said bearing is mounted and the lower screw 22 releases the upright 24 which supports the said shaft, thus permitting the said support 24 to be pivoted towards the rear, out of the way of the arbor 3. When the metal sleeve 2, upon which the paper coil form is mounted, has a tight fit on the arbor 3, its removal from the arbor is facilitated by using the pincer-like tool 25 shown in Fig. 1. One of the cylindrical jaws of this tool contains an inwardly extending pin 25a which is adapted to be received within a helical groove 30 in the arbor. Thus, when the jaws of the tool are closed about the inner end of the arbor and the arbor is rotated (as by means of the hand-wheel ll) the pin 25a will follow the groove 2a and urge the sleeve 2 outwardly toward and oil the free end of the arbor.

in the drawings. the metal when, as shown form upon which the paper and coils are wound said wire guides having comprises a split sleeve, the diameter of the said form will be effectively reduced upon its removal from the arbor 2. This obviously facilitates the removal of the paper coil-form from the said sleeve. However, since it is desirable to mount the still tacky paper-form I on a metal form during the thermosetting of the adhesive, it is usually expedient to employ a conventional (non-split) cylindrical form throughout the winding operation, since, in this event, the same form may be used during the setting process. In any event. when the winding operation has been completed, the paper form I, mounted on its temporary inner cylindrical metal support, is subject to a temperature higher than that used during the winding operation in order to set the resinous adhesive coatings on the paper and wire. A conventional oven (not shown) may be used for this purpose. Thereafter the paper coil form may be out into discrete lengths each individual to a single coil.

It will now be apparent that the present invention provides an improved apparatus for drywinding form-mounted coils and, furthermore one which provides a coil structure that will retain its shape throughout the assembly operation and is substantially immune to vibration, humidity and temperature changes. I

What is claimed is:

1. In a coil winding machine, a rotatable arbor, a movable support, a pair of wire guides mounted on said movable support in spaced array along a line parallel to the axis of rotation of said arbor, opposed faces between which a wire is adapted to pass in its journey to said arbor, a wire clamp mounted on the outer face of one of said guides in a position to receive said wire when said wire is placed therein upon completion of a winding interval, and lever means for moving said support and hence said wire guides and said clamp away from said mandrel with sufficient force to sever said clamped wire at a point intermediate said clamp and said arbor.

2. The invention as set forth in claim 1 and wherein said movable support is pivotally mounted at the front of said machine and is adapted to be moved by said lever means in the reverse direction through an are calculated to bring the severed end of the unwound portion of said wire in a position closely adjacent to said arbor.

3. In a coil winding machine, a rotatable arbor adapted to receive a sleeve about which a sheet havin a dry outer surface coating of a heat responsive adhesive is wrapped to form layers, means for heating said arbor whereby to render said coating tacky, a support adapted to be moved toward and away from said rotatable arbor, a roller mounted on said support for rotation in contact with the sheet when said support is in said first mentioned position whereby adjacent faces of said layer-wrapped sheet are bonded together by said adhesive into a composite cylindrical coil form having a tacky outer surface, and means to rotate said heated arbor to wind 9. wire upon said tacky outer surface of said cylindrical coil form.

HARRY V. KNAUF. JR.

No references cited. 

